From what series/year was that case? Looks quite different from my Mac Pro.

Its from a regular PowerMac G5....not a Mac Pro. The regular PowerMac has a huuuuge 600 watt power supply that takes up the whole bottom of the case. I think the Mac Pro has its PS on on the top, and I think its case is a little taller.

With the whole thing cleaned up, and better fans used to move more air through, I've been tweaking it bit by bit. Turns out my LED case fans that came with the Antec Twelve Hundred actually outperform the Corsair provided fans that came with the H70, by a decent amount no less! Must be that whole static pressure thing, I don't get how that works and don't know the specs on either fan type, but I know the Antec ones push way more air through and dropped my temps by another 3C after the flow-direction fix I had already applied.

Also turns out, if you have an Antec Twelve Hundred case, not only should you use it's fans instead of the Corsair ones provided, you should also totally ignore Corsair's advised flow direction recommendations. Using their recommended flow direction had me hitting 78C at 4.2Ghz and only 1.25 vcore. Unacceptable. Reversing it to the LOGICAL exhaust dropped temps 12C immediately. Then add the fan improvement from using the Antec's over the Corsair provided ones, and this is an AWESOME setup! Now I'm running 4.4Ghz at around 70C and I'm really really happy